Sonochemical induction of ABCA1 expression and compositions therefor

ABSTRACT

The present invention provides methods for transfecting cells (e.g., liver cells) to express ABCA1 and increase HDL in the blood. The compositions described herein comprise a pharmaceutically acceptable aqueous carrier containing sonochemically-active microspheres together with a plasmid DNA construct encoding an active form of ABCA1 and at least one promoter for the expression thereof. Preferably, the sonochemically-active microspheres comprise, consist essentially of, or consist of gas bubbles (e.g., a fluorocarbon gas, such as octafluoropropane) encapsulated within protein-containing or lipid-containing shells (e.g., human serum albumin shells). The microspheres are disruptable by exposure to ultrasonic acoustic energy to release the encapsulated gas.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a division of U.S. application Ser. No. 13/826,066, filed on Mar. 14, 2013, which is incorporated herein by reference in its entirety.

FIELD OF THE INVENTION

This invention relates to compositions comprising sonochemically-active microspheres and a plasmid encoding ATP-binding cassette transporter A1, and methods of inducing ATP-binding cassette transporter A1 expression in vivo.

SEQUENCE LISTING INCORPORATION

Biological sequence information for this application is included in an ASCII text file having the file name “SG-2-DIV-1-SEQ.txt”, created on Aug. 20, 2015 and having a file size of 44498 bytes, which is incorporated herein by reference.

BACKGROUND

High-density lipoprotein (HDL) is the largest of the five major groups of lipoproteins. Other lipoproteins include chylomicrons, very low-density lipoprotein (VLDL), intermediate-density lipoprotein (IDL), and low-density lipoprotein (LDL). HDL and other lipoproteins enable cholesterol and other lipids (e.g., triglycerides) to be transported within the bloodstream, despite their hydrophobic nature. About thirty percent of blood cholesterol is carried by HDL in healthy adults.

ATP-binding cassette transporter A1 (ABCA1) is an integral cell membrane protein that exports excess cholesterol from cells in conjunction with phospholipid that is necessary for the initial lipidation of ApoA1 to form nascent high density lipoprotein cholesterol (HDL-c). ABCA1 deficiency leads to very low plasma levels of HDL-c. In contrast, ABCA1 overexpression reportedly protected C57B1/6 mice from diet-induced atherosclerosis. Increasing ABCA1 transcription by enhancing its regulatory gene control by liver X factor (LXR) has led to the induction of not only HDL biogenesis, but also to an adverse increase in lipogenesis, leading to undesirable hepatic steatosis.

HDL-c is formed in the liver and the intestines by the lipidation of apolipoprotein A1 (apoA1) mediated by the ABCA1 transporter protein. Numerous studies of cultured cells, human HDL deficiencies, and animal models have shown that ABCA1 is a major determinant of plasma HDL levels and a potent atheroprotective factor. The role of ABCA1 in the liver for the formation of plasma HDL is well established, but it has been unclear whether stimulation of ABCA1 production will enhance lipidation and secretion of nascent HDL thereby resulting in an increase in plasma HDL-c levels.

The metabolism of HDL is complex and several factors contribute to the transport of cholesterol from arteries to the liver for excretion or re-use (reverse cholesterol transport). Some key players in reverse cholesterol transport include ABCA1, ABCG1, apoA1, apoE, LXR, Niemann Pick proteins 1 and 2 (NPC1 and NPC2) sterol regulating element binding protein (SREBP), CD36, acyl cholesterol acyl transferase (ACAT) and scavenger receptor A1 (SRA1). Many of these proteins have been considered as drug targets for enhancing blood HDL-c levels; however, the effects of targeting, enhancing the activity of, or otherwise interfering with the normal activity and expression of any of these individual proteins is unpredictable. High cholesterol also commonly is treated by inhibiting production of cholesterol in the liver (e.g., by inhibiting HMG-CoA reductase) or by inhibiting digestion of fats (e.g., by inhibiting bile acid production).

Plasma HDL-c and LDL-c levels are routinely measured as indicators of systemic atherosclerosis resulting in arterial blockage. HDL can remove cholesterol from within arteries and transport the cholesterol back to the liver for excretion or re-utilization. Individuals with higher levels of HDL-c have a reduced tendency for cardiovascular diseases. Low HDL-c cholesterol levels (less than about 40 mg/dL or about 1 mmol/L) are associated with increased risk of heart disease. In patients with Tangier disease (also known as “familial alpha-lipoprotein deficiency”), a rare inherited disorder, mutations in chromosome 9q31 lead to an inactive form of ABCA1. The inactive ABCA1 leads to severely depressed levels of HDL in the blood. Currently, there is no effective treatment for Tangier disease.

Because of the positive epidemiological correlation between HDL-c levels in the blood and reduced risk of heart disease, as well as the link between HDL and Tangier disease, there is an ongoing need for new methods of increasing blood HDL-c levels. The present application addresses this ongoing need.

SUMMARY OF THE INVENTION

The present invention provides compositions useful for transfecting cells (e.g., liver cells) to express ABCA1. The compositions described herein comprise a pharmaceutically acceptable aqueous carrier containing sonochemically-active microspheres together with a plasmid DNA construct encoding an active form of ABCA1 and at least one promoter for the expression thereof. The sonochemically-active microspheres comprise, consist essentially of, or consist of gas bubbles (e.g., a fluorocarbon gas, such as octafluoropropane or perfluorohexane) encapsulated within protein-containing or lipid-containing shells (e.g., human serum albumin shells). The microspheres are disruptable by exposure to ultrasonic energy (sonication) to release the encapsulated gas.

The following embodiments are provided as illustrative, non-limiting examples of the compositions and methods described herein.

Embodiment 1 comprises a composition useful for transfecting cells comprising a mixture of a plasmid vector encoding an active form of ATP-binding cassette transporter A1 (ABCA1) and sonochemically-active microspheres in a pharmaceutically acceptable aqueous carrier. The vector comprises an expressible open reading frame encoding the active form of ABCA1 and at least one sequence adapted to promote expression of the open reading frame in a mammalian cell. The sonochemically-active microspheres comprise gas bubbles encapsulated within shells comprising a protein, a lipid, or a combination thereof, the microspheres being disruptable upon exposure to ultrasonic acoustic energy to release the encapsulated gas bubbles.

Embodiment 2 comprises the composition of embodiment 1 wherein the microspheres have an average particle size in the range of about 0.5 to about 20 micrometers.

Embodiment 3 comprises the composition of embodiment 1 or embodiment 2 wherein the gas comprises a fluorocarbon gas.

Embodiment 4 comprises the composition of any one of embodiments 1 to 3 wherein the shells comprise human serum albumin.

Embodiment 5 comprises the composition of any one of embodiments 1 to 4 wherein the active form of ABCA1 has the amino acid sequence of SEQ ID NO: 1.

Embodiment 6 comprises the composition of any one of embodiments 1 to 5 wherein the open reading frame has the nucleotide sequence of SEQ ID NO: 2.

Embodiment 7 comprises the composition of any one of embodiments 1 to 6 wherein the at least one sequence adapted to promote expression of the open reading frame comprises a cytomegalovirus promoter.

Embodiment 8 comprises the composition of any one of embodiments 1 to 7 wherein the plasmid is present in the composition at a concentration in the range of about 0.5 to about 50 mg/mL.

Embodiment 9 comprises the composition of any one of embodiments 1 to 8 wherein the microspheres are present in the composition at a concentration in the range of about 10⁸ to about 10⁹ microspheres per milliliter.

Embodiment 10 comprises the composition of any one of embodiments 1 to 9 wherein the aqueous carrier comprises physiological saline, optionally buffered at physiological pH.

Embodiment 11 comprises the composition of any one of embodiments 1 to 10 further comprising at least one material selected from the group consisting of (a) a drug for treating a condition relating to lipid metabolism or transport, (b) a plasmid encoding a protein other than ABCA1 involved in lipid metabolism of transport, and (c) a plasmid encoding an siRNA that targets a protein involved in lipid metabolism or transport.

Embodiment 12 comprises the composition of any one of embodiments 1 to 11 wherein the plasmid encoding ABCA1 also encodes at least one material selected from the group consisting of (a) a protein other than ABCA1 involved in lipid metabolism of transport, and (b) an siRNA that targets a protein involved in lipid metabolism or transport.

Embodiment 13 comprises a composition useful for transfecting cells comprising a mixture of about 0.5 to about 50 mg/mL of a plasmid vector encoding an active form of ATP-binding cassette transporter A1 (ABCA1) and about 10⁸ to about 10⁹ microspheres per milliliter of sonochemically-active microspheres in a pharmaceutically acceptable aqueous carrier; wherein the vector comprises an expressible open reading frame encoding the active form of ABCA1 and at least one sequence adapted to promote expression of the open reading frame in a mammalian cell; and wherein the sonochemically-active microspheres comprise octafluoropropane gas bubbles encapsulated within shells comprising human serum albumin, the microspheres being disruptable upon exposure to ultrasonic acoustic energy to release the encapsulated gas bubbles.

Embodiment 14 comprises a method of transfecting a tissue in vivo to express an active form of ABCA1 in cells of the tissue, the method comprising the steps of (a) intravenously co-administering to a subject a plasmid vector encoding the active form of ATP-binding cassette transporter A1 (ABCA1), and sonochemically-active microspheres; wherein the vector comprises an expressible open reading frame encoding the active form of ABCA1 and at least one sequence adapted to promote expression of the open reading frame in a mammalian cell; and wherein the sonochemically-active microspheres comprise gas bubbles encapsulated within shells comprising a protein, a lipid, or a combination thereof, the microspheres being disruptable upon exposure to ultrasonic acoustic energy to release the encapsulated gas bubbles; (b) ultrasonically imaging the tissue of the subject to be transfected while the plasmid and microspheres of the composition are circulating through the vasculature of the tissue and thereby detecting the presence of the microspheres in the vasculature of the tissue; and (c) while the microspheres are present in the tissue, applying pulses of ultrasonic energy to the tissue at an acoustical energy level higher that that required for imaging and at a sufficient energy level to disrupt the microspheres and release the gas bubbles therefrom, the pulses of ultrasonic energy and release of gas bubbles thereby temporarily increasing the porosity of cells in the tissue to facilitate entry of the plasmid into the cells to effect transfection thereof.

Embodiment 15 comprises the method of embodiment 14 wherein the microspheres have an average particle size in the range of about 0.5 to about 20 micrometers.

Embodiment 16 comprises the method of embodiment 14 or embodiment 15 wherein the gas comprises a fluorocarbon gas.

Embodiment 17 comprises the method of any one of embodiments 14 to 16 wherein the shells comprise human serum albumin.

Embodiment 18 comprises the method of any one of embodiments 14 to 17 wherein the active form of ABCA1 has the amino acid sequence of SEQ ID NO: 1.

Embodiment 19 comprises the method of any one of embodiments 14 to 18 wherein the at least one sequence adapted to promote expression of the open reading frame comprises a cytomegalovirus promoter.

Embodiment 20 comprises the method of any one of embodiments 14 to 19 wherein the plasmid is administered in an aqueous carrier at a concentration in the range of about 0.5 to about 50 mg/mL.

Embodiment 21 comprises the method of any one of embodiments 14 to 20 wherein the microspheres are administered in an aqueous carrier at a concentration in the range of about 10⁸ to about 10⁹ microspheres per milliliter.

Embodiment 22 comprises the method of any one of embodiments 14 to 21 wherein the plasmid and the microspheres are administered as a mixture in one aqueous carrier.

Embodiment 23 comprises the method of any one of embodiments 14 to 21 wherein the plasmid and the microspheres are administered in separate aqueous carriers.

Embodiment 24 comprises the method of any one of embodiments 14 to 23 wherein an additional biologically active agent is co-administered along with the plasmid and microspheres.

Embodiment 25 comprises the method of embodiment 24 wherein the additional biologically active agent comprises at least one material selected from the group consisting of (a) a drug for treating a condition relating to lipid metabolism or transport, (b) a plasmid encoding a protein other than ABCA1 involved in lipid metabolism of transport, and (c) a plasmid encoding an siRNA that targets a protein involved in lipid metabolism or transport.

Embodiment 26 comprises the method of any one of embodiments 14 to 25 wherein the tissue comprises liver tissue, intestinal parenchymal tissue, or a combination thereof.

Embodiment 27 comprises use of a composition of any one of embodiments 1 to 13 to enhance high density lipoprotein cholesterol in the blood of a subject (e.g., to treat atherosclerosis).

Embodiment 28 comprises use of a composition of any one of embodiments 1 to 13 for the preparation of a medicament to enhance high density lipoprotein cholesterol in the blood of a subject (e.g., to treat atherosclerosis).

In a study conducted with rats, sonoporation of the liver in conjunction with a peripheral (tail vein) intravenous infusion of an aqueous composition containing ABCA1 plasmids and albumin-encapsulated fluorocarbon gas (octafluoropropane) microspheres resulted in a significant increase in plasma HDL-c levels relative to the baseline HDL-c levels for the rats. In this study, ABCA1 plasmid achieved a higher serum concentration of HDL-c than apoA1 plasmid. This finding is both surprising and novel the current understanding in this field is that the most effective method to increase hepatic secretion of HDL-c is to increase apoA1 synthesis. In fact, treatment with both the ABCA1 plasmid and the apoA1 plasmid was no better than an infusion of ABCA1 alone in this study.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 provides the amino acid sequence of human ABCA1 (SEQ ID NO: 1) utilized in the examples herein.

FIG. 2 provides the open reading frame nucleotide sequence of human ABCA1 (SEQ ID NO: 1) utilized in the examples herein.

FIG. 3 illustrates the nucleotide sequence of the plasmid (SEQ ID NO: 3) utilized in the examples herein.

FIG. 4 provides a schematic illustration of the ABCA1 plasmid utilized in the examples described herein.

FIG. 5 provides a graph of blood HDL-c in rats following sonochemical treatment with compositions comprising OPTISON microspheres and plasmids encoding ABCA1, apoA1, or a combination thereof.

DETAILED DESCRIPTION OF SELECTED EMBODIMENTS

In one aspect, the present invention provides compositions useful for transfecting cells to express ABCA1 comprise a pharmaceutically acceptable aqueous carrier containing sonochemically-active microspheres together with a plasmid DNA construct encoding an active form of ABCA1 and at least one promoter for the expression thereof. The sonochemically-active microspheres comprise, consist essentially of, or consist of gas bubbles encapsulated within protein-containing or lipid-containing shells. The microspheres are disruptable by sonication (i.e., exposure to ultrasonic acoustic energy), releasing the encapsulated gas.

In another aspect, the present invention provides a method of inducing ABCA1 expression in cells in vivo, and a method enhancing high density lipoprotein cholesterol in the blood. These methods comprise intravenously co-administering an ABCA1 plasmid and sonochemically active microspheres as described herein to a subject, ultrasonically imaging the a target tissue (e.g., the liver or intestinal parenchymal tissue) of the subject to detect when the microspheres are circulating through the vasculature of the tissue. The imaging typically is performed by external application of ultrasonic acoustic energy at a mechanical index (MI; which is defined as the peak negative acoustic pressure divided by the square of the imaginh frequency) less than about 0.4 MI. When the microspheres are detected in the target tissue, pulses of ultrasonic acoustic energy are applied to the tissue at an acoustic energy level higher than the energy level needed for imaging (typically greater than 1 MI, preferably greater than 1.3 MI, and up to about 2 MI), and of sufficiently high acoustic energy to disrupt the shells of the microspheres and release the gas bubbles encapsulated by the shells. The pulses preferably are applied at an acoustic frequency of about 1 to about 7 MHz. The acoustic energy of the pulses and the release of gas bubbles in the tissue temporarily increases the porosity of the tissue cell membranes (a process referred to herein as “sonoporation”).

Sonoporation of a tissue such as the liver comprises supplying ultrasonic acoustic energy pulses to the tissue with the ultrasound imaging probe. The pulses are applied while ultrasonically imaging the tissue so that the pulses are applied primarily when the microspheres (and thus also the co-administered plasmid) are present. The pulses typically are applied at a rate of about 6 to about 8 pulses per minute for a total of about 5 to about 20 pulses. The pulse duration typically is in the range of about 500 to about 2000 milliseconds per pulse. The acoustic energy pulses disrupt the microspheres and release the encapsulated gas. This disruption, combined with directly supplied acoustic energy makes the cells more porous to the plasmids, so that the plasmids can enter and transfect the cells. Once transfected, the cells transcribe protein via messenger RNA leading to synthesis of active ABCA1, which in turn enhances HDL formation and HDC-c concentration in the blood.

As used herein, the term “co-administration” and grammatical variations thereof, refers to administering two or more materials to the same individual during the same therapeutic session. Such co-administration can involve administering material separately, or together within the same composition. The co-administration can be simultaneous or can be temporally separated. In addition, sites of co-administration can be in the same location or different locations.

As used herein, the term “plasmid” and grammatical variations thereof refers to small circular DNA that is physically separate from, and can replicate independently of, chromosomal DNA within a cell (i.e., in an episome), and which commonly are found as small (e.g., about one thousand to about one million base pairs) circular, double-stranded DNA molecules in bacteria. Artificial plasmids are used as vectors in molecular cloning, serving to drive the replication of recombinant DNA sequences within episomes in the host cells without altering the chromosomal DNA of the host cells.

As used herein, the term “episomally transfected” and grammatical variations thereof refer to non-insertional (non-integrating) transfection with exogenous episomal nucleic acid, such as DNA, siRNA, RNA, or mRNA (e.g. a plasmid or other episomal vector) to produce a cell with unaltered chromosomal DNA, in which the a polypeptide encoded by the episomal DNA is expressed within the target cells (e.g., liver cells) without genomic integration of the exogenous DNA. As used herein, the term “episome” and grammatical variations thereof refers to closed circular DNA molecules that are replicated in the nucleus, and is intended to encompass exogenous plasmids introduced into host cells such as liver cells. Preferably, the plasmid encodes the active form of ABCA1 and also encodes regulatory elements (e.g., a promoter) to facilitate episomal expression of the ABCA1 protein.

As used herein, the term “active form of ABCA1” and grammatical variations thereof refers to the ABCA1 protein of SEQ ID NO: 1 and variations thereof comprising conservative substitutions in SEQ ID NO: 1 and sharing at least about 95 percent sequence identity (e.g., at least about 95, 96, 97, 98, or 99% sequence identity) with SEQ ID NO: 1 and retaining the lysine residues at positions 939 and 1952 of SEQ ID NO: 1.

Percentage values stated herein are on a weight-weight basis (i.e., “weight percent” or “percent by weight”) when referring to a concentration, and on a number basis when referring to a quantity or countable number of items, as the context will make evident and unless otherwise specified.

As used herein, a “therapeutically effective dosage” is an amount (e.g., a total of about 0.5 to about 10 mL of a single composition or co-administered compositions comprising about 0.5 to about 50 mg/mL of the ABCA1 plasmid and about 10⁸ to about 10⁹ of the microspheres per milliliter) such that when administered in conjunction with sonication of the liver, the plasmids transfect cells of the tissue to express the nucleic acid, subsequently resulting in enhanced HDL-c level in the blood, or other effects targeted by the therapy. The dosage and number of doses (e.g. single or multiple dose) administered to a subject will vary depending upon a variety of factors, including the route of administration, patient conditions and characteristics (sex, age, body weight, health, size), extent of symptoms, concurrent treatments, frequency of treatment and the effect desired, the concentration of plasmids in the composition, and the like.

Adjustment and manipulation of dosage ranges, as well as in vitro and in vivo methods of determining the therapeutic effectiveness of the composition in an individual, are well within the ability of those of ordinary skill in the medical arts. In some preferred embodiments, the dosage does not exceed about 5 mL of composition over a 10 minute period. Suitable safe dosages of ultrasonic contrast agents provide a useful guideline for use in the methods described herein. Such safe dosages are well known in the art and are documented in literature from ultrasonic contrast agent manufacturers.

The use of the terms “a” and “an” and “the” and similar referents in the context of describing the invention (especially in the context of the following claims) are to be construed to cover both the singular and the plural, unless otherwise indicated herein or clearly contradicted by context. The terms “comprising,” “having,” “including,” and “containing” are to be construed as open-ended terms (i.e., meaning “including, but not limited to,”) unless otherwise noted. Recitation of ranges of values herein are merely intended to serve as a shorthand method of referring individually to each separate value falling within the range, unless otherwise indicated herein, and each separate value is incorporated into the specification as if it were individually recited herein. All methods described herein can be performed in any suitable order unless otherwise indicated herein or otherwise clearly contradicted by context. The use of any and all examples, or exemplary language (e.g., “such as”) provided herein, is intended merely to better illuminate the invention and does not pose a limitation on the scope of the invention unless otherwise claimed. No language in the specification should be construed as indicating any non-claimed element as essential to the practice of the invention.

Sonochemically-active microspheres suitable for use in the compositions and methods described herein include any protein-based or lipid-based gas-filled microspheres (also known as “microbubbles”) that can be used as ultrasonic imaging contrast agents. The microspheres comprise a physiologically acceptable gas (e.g., a non-toxic gas such as nitrogen, air, oxygen, argon, or a fluorocarbon such as octafluoropropane (also known as “perflutren”) or perfluorohexane. The shell of the microspheres can comprise a protein (e.g., human serum albumin), a lipid material (e.g., phospholipids, phosphocholine lipids, and polyethoxylates thereof), or a combination thereof. Some lipid-based microspheres may also contain galactose in the shell. Protein-containing microspheres can include relatively small amounts (e.g., less than about 1 percent) of fatty acids (e.g., caprylic acid), amino acids or amino acid derivatives (e.g., N-acyltryptophan), or other formulation aids. The microspheres typically have a mean particle size (i.e., effective mean diameter) in the range of about 1 to about 10 micrometers (preferably about 1 to about 5 micrometers). Preferably, at least about 95% of the microspheres have a diameter of less than about 10 micrometers. The microspheres preferably are present in the composition at a concentration in the range of about 10⁸ to about 10⁹ of the microspheres per milliliter. The compositions described herein preferably are prepared by simple mixing of a microsphere suspension (e.g., as supplied by the manufacturer) with a solution of the plasmid or plasmids that are to be co-administered.

The pharmaceutically active aqueous carrier of the compositions comprises water (e.g., deionized, pyrogen-free water), and preferably includes one or more salts (e.g., sodium chloride, phosphate, citrate, and the like). In some preferred embodiments the aqueous carrier comprises physiological saline (about 0.9 percent NaCl), phosphate buffered saline, and the like. The carrier optionally can include other soluble materials (e.g., dextrose), preservatives, and the like, to provide a solution that is generally sterile, safe, isotonic and compatible with blood. Preferably, the compositions have a physiological pH (e.g., about pH 6.4 to 7.5).

Some preferred microsphere formulations useful in the compositions and methods described herein include the OPTSON brand microspheres (available from GE Healthcare), IMAGENT brand microspheres (developed by Alliance Pharmaceutical), and DEFINITY brand microspheres (available from Lantheus Medical Imaging, Inc.). Preferably, the compositions comprise human serum albumen encapsulated octafluoropropane microspheres, such as OPTISON microspheres.

According the manufacturer, OPTISON microsphere suspensions from GE Healthcare comprise about 5×10⁸ to about 8×10⁸ microspheres per mL of suspension. The microspheres comprise perflutren (octafluoropropane) gas bubbles encapsulated within shells of human serum albumin. The microspheres have a mean particle diameter of about 3 to about 4.5 μm with about 95% of the microspheres having a diameter of less than about 10 μm. The microspheres are suspended in a physiological saline solution (about 0.9 percent by weight NaCl in water). The compositions also can include less than about 1 percent caprylic acid, and less than about 1 percent N-acyltryptophan. Each milliliter of OPTISON microspheres reportedly comprises about 10 mg of human serum albumin, about 0.2 to 0.3 mg of perflutren, about 0.2 mg N-acetyltryptophan, and about 0.12 mg caprylic acid in 0.9% aqueous sodium chloride at a pH of about 6.4-7.4. The headspace of the vial containing the suspension is filled with perflutren gas. The manufacturer recommends that the injection rate should not exceed about 1 mL per second (maximum total dose should not exceed about 5 mL, in any 10 minute period, and maximum total dose should not exceed about 8.7 mL in any one patient study).

IMAGENT perflexane lipid microsphere composition (trade name previously IMAVIST) is an injectable suspension developed by Alliance Pharmaceutical. The microspheres reportedly comprise perflexane (perfluorohexane) microbubbles encapsulated in a lipid-based shell comprising 1,2-dimyristoyl-sn-glycero-3-phosphocholine (DMPC), hydroxyethyl starch and poloxamer (a nonionic triblock copolymer composed of a central hydrophobic chain of polyoxypropylene flanked by two hydrophilic chains of polyoxyethylene). The microspheres are suspended in a phosphate buffered saline solution.

According to manufacturer information, DEFINITY perflutren lipid microspheres are provided as an injectable suspension. The DEFINITY material is supplied as components that upon activation yield perflutren lipid microspheres. The material is supplied in a vial containing a clear, colorless, sterile, non-pyrogenic, hypertonic liquid, which upon activation with the aid of a VIALMIX brand activator, provides a homogeneous, opaque, milky white injectable suspension of perflutren lipid microspheres. The suspension of activated DEFINITY microspheres is administered by intravenous injection. The perflutren lipid microspheres are composed of octafluoropropane encapsulated in an outer lipid shell consisting of (R)-hexadecanoic acid-1-[(phosphonoxy)methyl]-1,2-ethanediyl ester, monosodium salt (abbreviated DPPA); (R)-4-hydroxy-N,N,N-trimethyl10-oxo-7-[(1-oxohexadecyl)oxy]-3,4,9-trioxa-4-phosphapentacosan-1-aminium-4-oxide inner salt (abbreviated DPPC); and (R)-α-[6-hydroxy-6-oxido-9-[(1-oxohexadecyl)oxy]5,7,11-trioxa-2-aza-6-phosphahexacos-1-yl]-ω-methoxypoly(ox-1,2-ethanediyl), monosodium salt (abbreviated MPEG5000 DPPE).

DPPA has a molecular weight of 670, empirical formula of C₃₅H₆₈O₈PNa, and following structural formula:

DPPC has a molecular weight of 734, empirical formula of C₄₀H₈₀NO₈P, and following structural formula:

MPEG5000 DPPE has an approximate molecular weight of 5750 represented by empirical formula C₂₆₅H₅₂₇NO₁₂₃PNa, and the following structural formula:

Prior to VIALMIX activation, the DEFINITY component vial reportedly contains 6.52 mg/mL octafluoropropane in the headspace. Each mL of the clear liquid reportedly contains 0.75 mg lipid blend (consisting of 0.045 mg DPPA, 0.401 mg DPPC, and 0.304 mg MPEG5000 DPPE), 103.5 mg propylene glycol, 126.2 mg glycerin, 2.34 mg sodium phosphate monobasic monohydrate, 2.16 mg sodium phosphate dibasic heptahydrate, and 4.87 mg sodium chloride in water (pH is 6.2-6.8). After activating the contents of the vial, each mL of the milky white suspension reportedly contains a maximum of 1.2×10¹⁰ perflutren lipid microspheres, and about 150 μm/mL (1.1 mg/mL) octafluoropropane. The microsphere mean particle size is about 1.1 μm to 3.3 μm, with 98% of the microspheres having a diameter of less than 10 μm.

Plasmid design. Plasmids generally comprise a strong viral promoter to drive the in vivo transcription and translation of the encoded gene (or complementary DNA, RNA, siRNA, or mDNA) of interest (which is present as an open reading frame). Intron A may can be included to improve mRNA stability and hence increase protein expression. Plasmids also typically include a strong polyadenylation/transcriptional termination signal, such as bovine growth hormone or rabbit beta-globulin polyadenylation sequences.

Because the plasmid provided the genetic material from which the protein of interest is expressed, optimizing vector design for maximal protein expression is desirable. For example, the codon usage can be adjusted to better conform to eukaryotic cells. Another factor to consider is the choice of promoter. Examples of promoters include the simian virus 40 (SV40) promoter, the Rous Sarcoma Virus (RSV) promoter, and the cytomegalovirus (CMV) promoter. In addition, expression rates can sometimes be improved by inclusion of enhancer sequences, adenovirus tripartite leader (TPL) sequences, or modifications to the polyadenylation and transcriptional termination sequences. Non-limiting examples of episomal plasmid vectors suitable for use as vectors for transfection of liver cells include SV40-based vectors, Epstein-Barr virus-based vectors, papilloma virus-based vectors, BK virus-based vectors, and the like, which are well known in the molecular genetics art.

Non limiting examples of episomal vectors suitable for use as non-integrating vectors for transfection of eukaryotic cells (e.g., primary MSC) include simian virus 40-based vectors, Epstein-Barr virus-based vectors, papilloma virus-based vectors, BK virus-based vectors, and the like, which are well known in the molecular genetics art.

In some embodiments, an additional biologically active agent is co-administered along with the plasmid and microspheres. Such additional biologically active agents include, for examples, a drug for treating a condition relating to lipid metabolism or transport, a plasmid encoding a protein other than ABCA1 involved in lipid metabolism of transport, and a plasmid encoding an siRNA that targets a protein involved in lipid metabolism or transport. Additionally, or alternatively, the plasmid encoding the active ABCA1 can also encode an a protein other than ABCA1 involved in lipid metabolism of transport, or a siRNA that targets a protein involved in lipid metabolism or transport.

Non-limiting examples of drugs for treating a condition relating to lipid metabolism or transport include HMG-CoA inhibitors, such as statins (e.g., atorvastatin, cerivastatin, fluvastatin, lovastatin, mevastatin, pitavastatin, pravastatin, rosuvastatin, simvastatin, and combinations thereof); bile acid inhibitors (e.g., cholestyramine, colestipol, colesevalam, and combinations thereof); fabric acid derivatives (e.g., clofibrate, gemfibrozil, fenofibrate) which may lower LDL-c and raise HDL-c; and niacin.

Examples of proteins involved in lipid metabolism or transport include, e.g., ABCA1, ABCG1, apoA1, apoA2, apoE, LXR, NPC1, NPC2, SREBP, CD36, ACAT, SRA1, and HMG-CoA. Such enzymes or siRNA targeting such proteins may be encoded by a plasmid co-administered with the ABCA1 plasmid, or in some cases can be encoded the same plasmid as the ABCA1.

Co-administration of a drug or a plasmid encoding a lipid metabolism/transport protein or siRNA can have the advantage of tailoring treatment to the specific condition suffered by the patient, by invoking multiple action sites, multiple metabolic targets, or both. For example, the materials to be co-administered can be selected e.g., to HDL-c and lower LDL-c in patients where both types of cholesterol are outside the recommended levels, or to raise HDL-c and lower total triglycerides, etc. In addition, different tissues may be transfected in a given subject, e.g., to target optimal tissues that may be involved in the particular lipid metabolic pathways of interest. For example, one tissue may be transfected to express one protein or siRNA, while a different tissue of the same subject may be transfected to express another protein of siRNA.

The following non-limiting examples are provided to illustrate certain features and aspects of the IP-MSC and methods described herein.

Methods and Procedures.

Male Sprague-Dawley rats (180-250 g) were purchased through Charles River Laboratories, Wilmington, Mass. All animal studies performed in an AAALAC, USDA, and OLAW accredited facility. Rats were housed in sterile cages (Alternative Design Manufacturing & Supply Inc., Siloam Springs, Ark.) and provided ad libitum access to standard commercial feed (Lab Diet; Purina Mills, St. Louis, Mo.) and water. Animals were maintained on a 12-hour:12-hour light:dark cycle, controlled temperature (approximately 24° C.) and controlled humidity (approximately 40%).

ApoA1 DNA Plasmids.

An apoA1 expression plasmid was constructed by subcloning an 804 by human apoA1 PCR cDNA product into expression vector pMIR0125 (Mirus Bio Corp, Madison, Wis.) containing human apoE hepatic control region (HCR), human ubiquitin C promoter and first intron. The final construct, pMIR0332-HCRUbC-h apoA1 was sequenced and the resulting clone matched the reported human apoA1 sequence. An ABCA1 expression vector was purchased from Origene (ABCA1 (NM 005502) Human cDNA ORF Clone, Cat. No. RC221861). FIG. 1 provides the amino acid sequence of ABCA1 (SEQ ID NO: 1) encoded in the open reading frame of the vector. FIG. 2 provides the nucleotide sequence of the ABCA1 open reading frame (SEQ ID NO: 2) of the vector, while FIG. 3 provides the nucleotide sequence of the entire vector (SEQ ID NO: 3). FIG. 4 provides a schematic map of the ABCA1 plasmid.

Infusion Method.

The plasmids (i.e., apoA1 plasmid, ABCA1 plasmid, or a combination of apoA1 and ABCA1 plasmids) were mixed with commercial OPTISON microsphere suspension for injection. Anesthetic: Inhalable gas mixture of oxygen and 1.5-3.0% isoflurane. A warming bed maintained rat body temperature at 37° C. Tail vein injections were performed using a 26 GA ¾-inch catheter. Mixtures: About 1 mL of OPTISON microspheres was mixed with (1) apoA1 DNA plasmid (approximately 8 mg in 1 mL), or (2) ABCA1 plasmid (approximately 7.3 mg in 1 mL), or (3) a combination of apoA1 and ABCA1 plasmids at the same concentrations per mL as used for the individual plasmids.

Plasmid Volume and Concentration of DNA.

All plasmids alone or in combination were mixed with OPTISON microspheres for about 15 to about 30 seconds prior to injection with a 3 mL injection syringe and then co-administered or co-infused. The infusion rate was manually performed at a timed rate of about 2 to 3 mL/minute and the total infusion duration was about 50 to about 70 seconds.

Ultrasound Equipment and Imaging and Therapeutic Parameters.

A VIVID I brand imaging system (GE Healthcare Systems, Milwaukee, Wis.) equipped with a 3S ultrasound probe was utilized for all liver sonications. All acoustic energy settings remained within FDA guidelines outlined for diagnostic use (ALARA principle). The rat liver was continually visualized using external ultrasound to verify appearance of OPTISON mixture within the liver vasculature and parenchyma. Low mechanical index (MI) ultrasound acoustic energy was used for imaging (e.g., <0.4 MI) whereas, higher MI (about 1.3 MI or greater) was used for therapy. No surgical abdominal incision was ever performed; external ultrasound was used to visualize the liver. The abdomen was shaved to eliminate surface hair.

The ultrasound parameters consisted of an continuous low mechanical index (MI<0.4) ultrasound exposure for “imaging” followed by a two-second “pulse” for therapeutic effect for a total of 10 “pulses.” A pulse was defined as a relatively higher (MI>1.3) burst of an ultrasound pulse. In sum, the “pulse” length was about 2 seconds with a pulse interval of about 8 seconds for a total of 10 pulses.

Blood Samples.

Three tail vein blood samples (0.5 ml) were collected over 6 days to establish a baseline serum HDL-c for each rat prior to treatment. After treatment with the plasmids in the OPTISON microsphere suspensions, blood samples were collected daily for three days and then after a three day hiatus. All blood samples were collected in glass test tubes containing a lithium heparin anticoagulant. The separated serum samples were analyzed using a clinical lipid panel test strip (PTS #1710 Lipid Panel Test for CARDIOCHEK PA CHOLESTEROL ANALYZER, Polymer Technology Systems, Inc., Indianapolis, Ind.) to quantify HDL values. Graphical data are reported as mean+1 SEM and statistical significance was determined by a two-sample t-test. The null hypothesis was rejected at P<0.05 and all statistical analyses were carried out using MINITAB12 (Minitab Inc., State College, Pa. USA).

Results.

FIG. 5 provides a graph of blood HDL-c levels of the treated rats, including the baseline level and levels for three days post-treatment. The selective hepatic transduction of ABCA1 through sonoporation described herein resulted in enhanced blood HDL-c relative to baseline HDL-c concentration. A single sonochemical treatment with an ABCA1 plasmid and sonochemically active microsphere composition in conjunction with sonication of the liver resulted in a 15% increase in HDL-c. A surprising finding in this study was that the ABCA1 plasmid therapy resulted in superior increases in HDL-c relative to treatment with an apoA1 plasmid or the combination of ABCA1 and apoA1 plasmids under the same sonication conditions.

Preferred embodiments of this invention are described herein, including the best mode known to the inventors for carrying out the invention. Variations of those preferred embodiments may become apparent to those of ordinary skill in the art upon reading the foregoing description. The inventors expect skilled artisans to employ such variations as appropriate, and the inventors intend for the invention to be practiced otherwise than as specifically described herein. Accordingly, this invention includes all modifications and equivalents of the subject matter recited in the claims appended hereto as permitted by applicable law. Moreover, any combination of the above-described elements in all possible variations thereof is encompassed by the invention unless otherwise indicated herein or otherwise clearly contradicted by context. 

We claim:
 1. A method for increasing HDL-cholesterol levels in the blood of a subject, the method comprising the steps of: (a) intravenously co-administering to the subject a plasmid vector encoding the active form of ATP-binding cassette transporter A1 (ABCA1), and sonochemically-active microspheres; wherein the vector comprises an expressible open reading frame encoding the active form of ABCA1 and at least one sequence adapted to promote expression of the open reading frame in a mammalian cell; and wherein the sonochemically-active microspheres comprise gas bubbles encapsulated within shells comprising a protein, a lipid, or a combination thereof, the microspheres being disruptable upon exposure to ultrasonic acoustic energy to release the encapsulated gas bubbles; (b) ultrasonically imaging a tissue of the subject to be transfected by the plasmid while the plasmid and microspheres are circulating through the vasculature of the tissue and thereby detecting the presence of the microspheres in the vasculature of the tissue; and (c) while the microspheres are present in the tissue, applying pulses of ultrasonic energy to the tissue at an acoustical energy level higher than a level required for imaging and at a sufficient energy level to disrupt the microspheres and release the gas bubbles therefrom, the pulses of ultrasonic energy and release of gas bubbles thereby temporarily increasing the porosity of cells in the tissue to facilitate entry of the plasmid into the cells; wherein the plasmid transfects the cells and elicits production of an increased level of HDL-cholesterol in the blood of the subject compared to the HDL-cholesterol level in the blood of the subject prior to administering the plasmid.
 2. The method of claim 1, wherein the microspheres have an average particle size in the range of about 0.5 to about 20 micrometers.
 3. The method of claim 1, wherein the gas bubbles comprise a fluorocarbon gas.
 4. The method of claim 1, wherein the shells comprise human serum albumin.
 5. The method of claim 1, wherein the active form of ABCA1 has the amino acid sequence of SEQ ID NO:
 1. 6. The method of claim 1, wherein the open reading frame has the nucleotide sequence of SEQ ID NO:
 2. 7. The method of claim 1, wherein the at least one sequence adapted to promote expression of the open reading frame comprises a cytomegalovirus promoter.
 8. The method of claim 1, wherein the plasmid is administered in an aqueous carrier at a concentration in the range of about 0.5 to about 50 milligrams per milliliter.
 9. The method of claim 1, wherein the microspheres are administered in an aqueous carrier at a concentration in the range of about 10⁸ to about 10⁹ microspheres per milliliter.
 10. The method of claim 1, wherein the plasmid and the microspheres are administered as a mixture in one aqueous carrier.
 11. The method of claim 1, wherein the plasmid and the microspheres are administered in separate aqueous carriers.
 12. The method of claim 1, wherein the plasmid and microspheres are administered in an aqueous carrier comprising physiological saline, optionally buffered at physiological pH.
 13. The method of claim 1, wherein the plasmid encoding ABCA1 also encodes at least one material selected from the group consisting of (a) a protein other than ABCA1 involved in lipid metabolism of transport, and (b) an siRNA that targets a protein involved in lipid metabolism or transport.
 14. The method of claim 1, wherein an additional biologically active agent is co-administered along with the plasmid and microspheres.
 15. The method of claim 14, wherein the additional biologically active agent comprises at least one material selected from the group consisting of (a) a drug for treating a condition relating to lipid metabolism or transport, (b) a plasmid encoding a protein other than ABCA1 involved in lipid metabolism of transport, and (c) a plasmid encoding an siRNA that targets a protein involved in lipid metabolism or transport.
 16. The method of claim 1, wherein the tissue comprises liver tissue, intestinal parenchymal tissue, or a combination thereof.
 17. A method for increasing HDL-cholesterol levels in the blood of a subject, the method comprising the steps of: (a) intravenously administering to the subject a composition comprising a mixture of a nucleic acid encoding an expressible open reading frame and sonochemically-active microspheres in a pharmaceutically acceptable aqueous carrier; wherein the nucleic acid of the mixture consists of a plasmid vector, the expressible open reading frame consists of an expressible open reading frame encoding the active form of ATP-binding cassette transporter A1 (ABCA1), and the plasmid vector also includes at least one sequence adapted to promote expression of the open reading frame in a mammalian cell; and wherein the sonochemically-active microspheres comprise gas bubbles encapsulated within shells comprising a protein, a lipid, or a combination thereof, the microspheres being disruptable upon exposure to ultrasonic acoustic energy to release the encapsulated gas bubbles; (b) ultrasonically imaging a tissue of the subject to be transfected by the plasmid vector while the composition is circulating through the vasculature of the tissue and thereby detecting the presence of the microspheres in the vasculature of the tissue; and (c) while the microspheres are present in the tissue, applying pulses of ultrasonic energy to the tissue at an acoustical energy level higher than a level required for imaging and at a sufficient energy level to disrupt the microspheres and release the gas bubbles therefrom, the pulses of ultrasonic energy and release of gas bubbles thereby temporarily increasing the porosity of cells in the tissue to facilitate entry of the plasmid into the cells; wherein the tissue comprises liver tissue, intestinal parenchymal tissue, or a combination thereof; the plasmid transfects the cells and elicits production of an increased level of HDL-cholesterol in the blood of the subject compared to the HDL-cholesterol level in the blood of the subject prior to administering the composition; and the pulses are applied at a rate of about 6 to 8 pulses per minute, with pulse durations in the range of about 500 to about 2000 milliseconds per pulse, and at an acoustic energy mechanical index (MI) of about 1 to about 2 MI.
 18. The method of claim 17, wherein the microspheres have an average particle size in the range of about 0.5 to about 20 micrometers.
 19. The method of claim 17, wherein the gas bubbles comprise a fluorocarbon gas, and the shells comprise human serum albumin.
 20. The method of claim 17, wherein the open reading frame encoding the active form of ABCA1 has the nucleotide sequence of SEQ ID NO:
 2. 21. The method of claim 17, wherein the at least one sequence adapted to promote expression of the open reading frame comprises a cytomegalovirus promoter.
 22. The method of claim 17, wherein the plasmid is administered in an aqueous carrier at a concentration in the range of about 0.5 to about 50 milligrams per milliliter, and the microspheres are administered in an aqueous carrier at a concentration in the range of about 10⁸ to about 10⁹ microspheres per milliliter.
 23. The method of claim 17, wherein an additional biologically active agent is co-administered along with the plasmid and microspheres.
 24. The method of claim 23, wherein the additional biologically active agent comprises at least one material selected from the group consisting of (a) a drug for treating a condition relating to lipid metabolism or transport, (b) a plasmid encoding a protein other than ABCA1 involved in lipid metabolism of transport, and (c) a plasmid encoding an siRNA that targets a protein involved in lipid metabolism or transport. 